.nav {
    border: none;
  }
  .nav li {
    border: 1px solid #ccc;
  }
  .nav li .title {
    background-color: #f5f5f5;
    font-family: "微软雅黑", sans-serif;
    font-size: 16px;
    cursor: pointer;
    height: 39px;
    box-sizing: border-box;
    display: inline-block;
    font-weight: normal;
    width: 100%;
    padding: 10px 15px;
    position: relative;
  }
  .nav li .title div {
    position: absolute;
    right: 5px;
    top: 15px;
    width: 0;
    height: 0;
    border-left: 10px solid transparent;
    border-right: 10px solid transparent;
    border-top: 10px solid #000;
    border-bottom: 10px solid transparent;
  }
  .nav li .min-nav {
    background-color: #fff;
    display: flex;
    flex-wrap: wrap;
  }
  .nav li .min-nav p {
    width: 93px;
    height: 39px;
    text-align: center;
    line-height: 39px;
    box-sizing: border-box;
    border: 1px solid #ccc;
  }
  